Calibrations For High Gain Antennas

High gains, such as horn antennas, have narrow beamwidth. They do not see ground plane when placed in a close distance. In that case, the calibration is in free-space condition.

Use Of Antennas For Radiated Emissions Testing

Radiated emissions tests are defined in ANSI C63.4 in the US or the equivalent EN standards in Europe. The test setup is very similar to the antenna calibration setup. A large flat, unobstructed metal ground plane is used. The equipment under test is set on a low dielectric table, which is 80 cm high. The table is
placed on a turntable, which can provide a full 360° scan. The receive antenna is scanned from 1 to 4 m for both horizontal and vertical polarization, and the maximum
readings are recorded and compared to the standards. For emissions measurements, it is recommended to use free-space antenna factor. This is despite the fact that the measurements are not performed in a free space environment. The true antenna factors in the specific test environment are height dependent. The free space AF provides a good compromise.


Use Of Antennas For Radiated Immunity Testing
Most immunity tests are performed per European standard EN 61000-4-3. It requires the establishment of a uniform field plane where the EUT would be. The typical setup is illustrated in Figure below.



The antenna power handling capability is an important parameter in such a test. Many antennas are designed to have superior performance in balance and impedance matching, and not designed to handle high powers required in an immunity test. For an immunity antenna, the balance is not as important, since the purpose is to establish a known electromagnetic field. In the setup shown, the isotropic field probe is the key in setting up a calibrated field.